Process for purifying and increasing combined calcium of calcium sulfonates



United States O lice s Claiins.- c1. asp-33.4

This invention relates 'to an improvement 'in the manufacture ofoil-soluble calcium sulfonates-ir'om petroleum sulfonic acids, e. g.mahogany acids, or from synthetic alkyl aromatic ,sulfonic acids.

This invention is more specifically concerned with a step of producing.a high alkalinity calcium sulfonate while eliminating residual calciumchloride'contaminaut of the sulfonate. The high alkalinity in the form:of

combined calcium in calcium sulfonate is desirable for satisfactorymotor oildetergents. 1

By the method of the present invention the residual calcium chlorideimpurity or purposely added calcium chloride is made'to react with analkalimeta'l hydroxide,

e. g. strong NaOH aqueous solution,- added inea-controlled amount toprevent the presence ofexcess' sodium hydroxide in an oil solution ofthecalcium sulfonate preferably before it is heated and filtered.

The controlled addition 'ofthe caustic solution t=the oiljsolution ofthe calcium :sulfona-te containing a small amount: of calcium.chlorideeliminates the solids handling difiiculties-normally associatedwith the conventionalli-mingpnocess, wherein solid or drycalcium-hydroxide is employed as the liming agent. 1

The sodiumhydroxide reacts with the residual calcium chloride fromdouble decomposition of an or ig-iualisodium .sulfonate with addedcalcium clrloride'in :thefdr- 0.5mole residual calcium chloride per moleof sulfonate tends to be present. Generally,this proportion isnorniallyobtained. Various methods have been used and proposed forremoving-the calcium chloride. Some methods are intended to eliminatethe salt by precipitation.

-0thers use washing. Such methods give difliculties in the formation ofthick solid-like concentrates,which flow with difliculty and are notsuitable for dehydration. Still othermethods involve a further additionof calcium hydroxi'de which gives handling and other difiiculties.

In'using the method of the present invention,*that of adding acontrolled proportion of aqueous sodium hydroxide to react with thecalcium chloride in the 'oil'solution of calcium sulfonates, "it hasbeen observed that the finely'divided and freshly precipitated calciumhydroxide thus formed is highly soluble in the 'oil' solution of thecalciumsul-fonates. When sucha'solut'ion is heated to drive ofi waterand then filtered whilehot, sodium chloride is filtered out withoutsubstantial lowering of the calcium content of the-oil solution.

The following examples showcomparative results in -usingdry lime and astrong aqueous alkaline solution for treating samples of a neutralcalcium sul for'iat'e oil solution containing 30 weight percent'calciumsulfonate having a molecular weight of 934 and containing "about "3;4'w'eigh't percent of calcium chloride.

EXAMPLES *In :one experiment 0.75 mole of the "dry calcium hy-Edroxidewasadded per mole 'of calcium sulfonate in'the solution toprovide a substantial excess of lime with respect to the calciumchloride in' the oil solution of calcium sulfonate.

To the other sample, only a suflicientamount of strong vaqueous'c'austic solution was added as was needed-to react with :theresidual calcium ch1oride,"about Bill 3% less ona mole equivalent basis.

- Both samples were then subjected to' the-samekind of dehydration andfiltering after whichthe neutr aliz-ation mation .of calcium sulfonate.The reaction of the-sodium hydroxide-"with :the calcium chloride forms afresh precipitateof finely divided calcium hydroxide.

Under these conditions the reaction isinthe direction toward theprecipitate formation, and as the amount of sodium hydroxide addediscalculated to rea'ctwith the residual calcium chloride'present inuptoja-bout stoichiometrical amount (2 moles NaOH per mole CaCl there isno excess sodium hydroxide left as a residuein .the calcium sulfonate.

Y ,SolidsHand1lueProb1em- No' Yes Various known methods of "forming thecalciur'n'sulfonate are typified by U. S. Patent 2,467,176, whereinresidual calcium chloride is removed from the oil solution by washing.

In the usual well known process of forming the sulfonates, a hydrocarbonoil, e. g. a phenol raflinate, obtained in making white oil or asynthesized C alkyl aromatic hydrocarbon is treated with oleum to formthe sulfonic acids. The acid oil is separated from the heavier sulfuricacid sludge, then is neutralized with sodium car- 'bonate to form sodiumsulfonates which are soluble in the oil.

To convert the sodium sulfonates to calcium sulfonates an excess amountof calcium chloride brine is admixed with the oil solution of the sodiumsulfonates, and the resulting mixture is heated with stirring at 200 F.for

number of the samples was determined. The sodium hydroxide treatedsul-fonate sample-shows a comparatively-similar high alkalinity to thesulfonate sample treated with a larger proportion of dried calciumhydroxide.

Table I.-Compararive tests onfllka'lizing Casulfona-te 1 usin'g solidCa(OH') and "NaOH A1kalizlng.A-gent -25%*Na0H Solid u i GatQH):

Mole Equivalent of Agent:

NaOH] Oa(0H)z mole Ca Sulfonate 0.75

Mixing and Dehydrating 'Iemp., F 300 300 N eutralizatlon N 0., mg.KOH/g. Sample 15. 3 16. 2

1 Concentrations: 0a sulionate in oil, wt. percent: 30.0. (laOlg, wt. fii s e d o i'i equivalent moles of 0a(OH)z/l mole calcium sulfonate.

' Determined by back titration with acid per A. S. T. M.

In tests such as shown above for illustrative purposes, practically thesame high alkalinity of about 16 Neut. No. was obtained in the calciumsulfonate solutions by the freshly precipitated lime formed by addition.of the NaOH as was obtaind by addition of solid Ca(OH) Quite unlikeknown methods of treating calcium sulfonates, the present method isadapted for the addition of calcium chloride and sodium hydroxide inaccurately measured proportions to a petroleum oil solution of calciumsulfonates which may or may not be contaminated by small amounts ofcalcium chloride. The reaction between the sodium hydroxide, calciumchloride and the calcium sulfonate brings about the formation of a basiccalcium sulfonic acid salt which remains in solu- Patentefd May 6, 1958'mole Ca Sultanate 0.50

. which followsthe reaction and dehydration. ferred concentration of thesulfonates is about 30 wt. percent in thetoilduring ;the reaction andfiltering; The r reaction anddehydrationqoccur at temperaturesin thespasms v remove precipitatedsodium chloride.

' tion when the, solution is dehydrated and thenfiltered to" p In addingaqueous caustic or alkali metal hydroxide to i l the oil solution, thisaddition may be made to the calcium sulfonate preferably dissolvedinhydrocarhonwoil or similar organic solvent. for. the sulfonates, :Thecalcium sulfonate concentration in the. solution is, usually from about30'to 50 wt. percent but may varyover ,a wider range.

It is advantageous to. have about} mole of calcium chloride presentper;mole of thecalcium. sulfonate in ob- ,taining the dcsiredhigh alkalinityby reaction withadded caustic. Somewhat smaller or larger amounts ofresidual calcium chloride may be present in the oil solution; then 1calcium chloride may be added ,totmake up for the deficieucy, or somecalcium chloride may be'removed from the solution, :if desired, beforeaddition of caustic.

The alkalimetal hydroxide ispreferably added as a strong caustic aqueoussolution in, controlled amount to facilitatethelater dehydration. 1

Following the addition of the caustic solution to a concentratedoilysolution of calcium sulfonates containing the required calciumchloride, more oil may be added to dilute the mixture in order to aidinmixing and filtering A prerange of 80 to 300 F., and can be made totakeplace simultaneously. The filtering is carried out at elevatedtemperatures close to 300 F. and with the help of filter of the. oilcontaining thecdissolved calcium sulfonates 1 aids,e. g. diatomaceousearth. A clear filtered solution combined. with the freshly formedcalcium hydroxide is obtained. 1

Further comparative teststwere. made to demonstrate advantages overother methods which do not alkalize substantial amounts of calciumchloride .with an alkali metal hydroxide. V In thesetests samples of an,oilcontaining tain the best quality basic calcium sulfonate-oilproduct,

,the proportions of reactants in the oil should be of the order of 2moles NaOH/l mole CaCl,/2 moles Ca sulfonate. If the amount of calciumchloride alkalized (converted to Ca(OH),) is much less, then the sodiumcontent is increased in the final product. If it is much more, thedesired alkalinity increase is not obtained.

v 'I-Iaving described the invention, it is claimed as follows! 1. Amethod of purifying an oil solution of calcium sulfonate and increasingthe alkalinity thereof, saidsolu- .-tion containingresidual calciumchloride, which com- .droxide per mole of calcium chloride. and per 2moles of calcium sulfonate, heating the resulting mixture underconditions and for a time sufficient to convert the calcium chloride tohydroxide and convert the sodium hydroxide Lto sodium. chloride attemperatures in the range of 80 to 300. E, dehydrating the ml solutionto leave basic calcium sulfonate in solution andprecipitate the sodiumchloridefrom the solution, then filtering the solution to remove sodiumchloride.

. 3. In the, formation of a petroleum oil solution of basic calciumsulfonate, the improvement which .comprises admixing with petroleum oilsolution of about30 ..to wt. percent oil-soluble calcium sulfonates frompetroleum .sulfonic acids containing a substantial amount of calciumchloride a strong aqueous solution of sodium hydroxide in an amountsuflicient to react 2 moles of sodium hydroxide per mole of the calciumchloride and per .2 ,moles of the calcium sulfonate, heating theresulting mixture to about 300 F. until fresh calcium hydroxide andsodium chloride precipitate are formed in .said solution, simultaneouslydriving off water fromthe solution at about 300 F., then while thesolution is still hot filtering said solution to remove sodium chloridepre- 32.22% calcium sulfonate and about 0.5 mole ofcalcium chloride permole of sulfonate were used. .Theimproved alkalinity obtained with NaOHreaction is shown in the followingTableII. v H 1 it r Table II M 1 INeutraliv Condition zatlon No.

(1) 0.3 mole dry lime added ole 0a Sultanate 9. 8i (2) 0.3 mole limeQQIIlVLO! aOH added/mole CaBultonate. 10.81

Tests showed that no substantial increasewas made in sodium contentbyadding the NaOH after dehydrating and filtering and this is a desirablefactor. Toavoid excess of alkali metal in the finished product and toobcipitate therefrom.

References Cited in thefile of this patent 1 UNITED STATES PATENTS2,413,311 Cohen Dec. 31, "1946 2,453,690 Bray Nov. 16, 1948 2,501,731'Mertes Mar. 28, 1950

1. A METHOD OF PURIFYING AN OIL SOLUTION OF CALCIUM SULFONATE ANDINCREASING THE ALKALINITY THEREOF, SAID SOLUTION CONTAINING RESIDUALCALCIUM CHLORIDE, WHICH COMPRISES ADDING TO SAID SOLUTION AN AMOUNT OFAQUEOUS SODIUM HYDROXIDE SUFFICIENT TO CONVERT SUBSTANTIALLY ALL OF THECALCIUM CHLORIDE TO CALCIUM HYDROXIDE SOLUBLE IN SAID SOLUTION, HEATINGSAID SOLUTION TO DEHYDRATE AND PRECIPITATE SODIUM CHLORIDE AND REMOVINGTHE PRECIPITATED SODIUM CHLORIDE FROM SAID SOLUTION.